130 RAPID POPULATION GF scanty official data suggests that the birth rate may be relatively low developed country, but this is quite uncertain.* Breakthroughs in other regions are less dramatic but are impress range of cultures and conditions represented. Reductions in natali curring among very diverse peoples. They are occurring in Ceylon, land of Asia," in which late marriage as well as birth control hav about lower birth rates among both the Sinhalese and the Ceyk (originally immigrants from south India). Change is occurring in countries of Mauritius, Reunion, and the Seychelles, with their mixe tions of Africans and Asians, and in the West Indies among peoples c origin (Barbados and Jamaica), of mixed African and Asian origin (' and of chiefly European origin (Puerto Rico and Cuba). In the W major reductions in the birth rate are also reported in the Frendh islands of Guadelupe and Martinique and in the Netherlands Antill* mainland a rapid reduction in natality seems to be occurring in C< the most socioeconomically advanced of the countries of Central A: well as in Chile, one of the most advanced countries of South Amen- Finally, a significant development has been the appearance in v< years of fertility declines among peoples of Islamic tradition. Unt: cently Islam was far more effective than Catholicism in its resistar spread of fertility control (8). Now rapid reductions in birth rat< curring in Albania, in the other Islamic populations of southeastei (e.g., in Yugoslavia), in several of the Soviet republics of Islamic her quite possibly in Turkey and Tunisia (7, 9). As cultural barriers are being breached, so for the first time raj tions in birth rates are occurring in a number of tropical countries, scattered as Malaysia, Ceylon, and the West Indies. Very recent experience has demonstrated that the fertility tran cross major cultural frontiers and is indeed doing so in many areas. The evidence given above should be tempered by two observatior First, the countries concerned are generally rather small and, int enough, many are islands. Several of them are experiencing unusu social and economic development and, in some, birth rates have bee; by the emigration of young adults. They are also likely to be countr frontiers between major cultural regions and hence more vulnerablt nal influence than the larger countries. We do not in fact know wr to what extent change is under way in other and larger countries, occurring, it seems likely that the transition is at an earlier stag< these cautions, there is increasing evidence that natality redu< making headway in a wide variety of cultural situations in less i The estimate of the birth rate in mainland China used by the United Natconditions.